The present invention relates to printed circuit boards and more particularly to printed circuit boards having conductive pads formed on upper and lower surfaces near an edge of a board main body that make electrical connection with sliding electrical contacts.
An example of a printed circuit board of this type is shown in FIG. 5 as disclosed in Japanese Patent Disclosure No. 96-241755. Printed circuit board 100 comprises a board main body 101 having multiple conductive pads 102 formed on upper and lower surfaces of the main body. The conductive pads 102 are arranged in one row on both surfaces of the board main body 101 along and near edge 103 of the main body.
On the other hand, housing 111 of card edge connector 110 has a board-receiving slot 112 to accommodate the printed circuit board 100 inside of which multiple electrical contacts 113 are arranged in two mutually-opposed rows. When the printed circuit board 100 is inserted in the board-receiving slot 112, the contacts 113 make sliding electrical connection with respective conductive pads 102 arranged on the upper and lower surfaces of the printed circuit board 101. Latch-ejection members 114, the purpose of which is to latch the printed circuit board 100 in the board-receiving slot 112 or to eject it therefrom, are pivotally mounted at the ends of housing 111 by pins 115 so that the latch-ejection members 114 operate in a pivotal manner relative to the housing 111.
However, in some cases, the conductive pads 102 on the upper and lower surfaces of the printed circuit board 101 must be connected together by means of via holes when such pads are used as grounding pads. In such cases, the via holes are positioned near the ends of the conductive pads 102, i.e., at the ends opposite to the edge 103 of the board main body 101 so that the via holes would not interfere with contacts 113. The problem is that in such cases, the width of the conductive pads 102 must be increased in the direction of the gliding of the contacts 113 by a portion equal to at least the diameter of the via holes, thus making it necessary to increase the width of the printed circuit board 100 by the same amount.
Another problem is the fact that in the process of insertion of the printed circuit board 100 in the board-receiving slot 112, the contacts 113 rub against the edge 103 of the printed circuit board 100. As a result, a powdered substance is produced that may affect the electrical connections between the contacts 113 and the conductive pads 102.
Therefore, the purpose of the present invention is to provide a printed circuit board with conductive pads formed on upper and lower surfaces of a board main body that has a smaller width in the direction of sliding engagement with electrical contacts and that makes it possible to establish a smooth electrical connection with the electrical contacts even if a powdered substance is produced.
The printed circuit board according to the present invention has conductive pads formed near an edge of the main body of the circuit board on upper and lower surfaces thereof so that the conductive pads establish electrical connections with electrical contacts as the contacts slide from the edge of the board main body inwardly, and by the fact that via holes establish electrical connection between conductive pads on the upper and lower surfaces of the main body of the circuit board and that such via holes are located in the paths of the contacts.
Contact members of the electrical contacts enraging the conductive pads have a curved or arcuate surface, the radius of which is greater than the radius of the via holes, thus providing for a better electrical connection.